Rust inhibitors



United States Patent RUST INHIBITORS James W. Amick, Highland, Ind., assignor to Standard Oil Company, Chicago, 11]., a corporation of Indiana invention specifically, may be produced by the reaction of a suitable polybutene with maleic anhydride and the resultant product hydrolyzed to the acid form. Particularly preferred polybutencs have an average molecular 1 6 1967 S No. 678 170 weight of between 700 and 900. No i fi ggf g 5 The products of the present mvent1on may be prepared s CL 4 70 2 Cl i by reacting maleic anhydride with a suitable polybutene,

and hydrolyzing the resulting product to form the acid.

DESCRIPTION OF PREFERRED EMBODIMENTS ABSIRACT OF THE DISCLOSURE 10 Th f n I b 11 t t e o owmg examp es are given ywayo 1 us ra 10H, Rust mhltmrs for fuels .compnsmg Polyand the invention should not be construed as limited butene substltuted succmlc ac1d wherem the polybutene thereto substituent has an average molecular weight in the range Example I of 450 to 1100.

175 grams of maleic anhydride 1.79 moles) was added to 1254 grams of polybutene having an average molecular PACEGROUND OF THE q weight of 850. The reactants were heated for about two Thls mventlop relates to a w class of m i ltors hours at 392 F., and stirred overnight at 195200 C. {more pamcularly to subsntuted succlmc and rust The temperature was raised to 225 C., and excess maleic i i anhydride was removed b blowing with nitrogen gas. 11 f 1 1 k h t 1 Y DISH such as Jet file erosme: i er The product was then filtered, and hydrolyzed to the d1- furnace 011, diesel fuel, et c., require rust lnhlbltors as acid by heating to F and adding about 27 grams corroslon protect on for p1pelmes and the product d1s- (1.5 moles) of water. The reactants were then stirred trrbut1on system 1n general as well as the protectlon of about one hour with reflux customer tanks and equipment. Due to the increased se- I verity of use of distillate fuels under conditions providing Example II high corrosion rates, more effective products are neces- A product was btained using the procedure of Example sary as comPared to the PIT/Sent commercial Eroductsf I except the polybutene was of 460 average molecular has been found that the lower molecular welght substl- Weight tuted succinic acid or anhydride, or substituted succinic 30 Example 111 anhydrides do not provide the high degree of rust inhibid h d tion as is presently desirable. A possible explanation of pro not a obiamed t e prose me of the poorer performance of the anhydride is that the ang e FE the Po ybutene was of 380 average molec' hydride may react with polar groups present in the fuel u ar Welg E 1 IV in which it is to be used, e.g., amino groups. Carboxylic Xamp e acids and carboxylic acid amine salts have also been used A product was obtained using the procedure of Example as rust inhibitors but have not been entirely satisfactory. I except the polybutene was of 250 molecular weight.

SUMMARY OF THE INVENTION Examples V-VIII I have now found that the novel compositions of the 40 In these examples the reactants of Examples I-IV were present invention provide superior rust inhibition than used to produce the products of Examples V-VIII respecwas previously known with products of the prior art. It has tively, except hydrolysis to form the acid was not done. been discovered that high molecular weight substituted The products of the above examples were tested in fursuccinic acid is a very effective rust inhibitor. It has also nace oils (identified below as fuel A, B or C) in the fourbeen found that the present inhibitors are more effective hour static rust test, which is as follows: a polished black when used at low concentrations, and with other distillate iron strip is immersed in 100 mililiters of fuel in a 4- fuel additives, than was previously known. There is also ounce tall-form bottle for 30 minutes. After 30 minutes, a substantial saving in cost with the use of the present 10 milliliters of salt water (0.25% sodium chloride) is additives. added. The bottle is stoppered and rolled on its side for Broadly, the compositions of the present invention com- 1 minute. The bottle is stood on end and is tapped 5 times prise polybutene substituted succinic acids wherein the to knock down excess water adhering to the metal. The polybutene substituent has an average molecular weight strip is observed after 4 hours. Specks of rust in the oil of between about 450 and 1100. The most eflective inphase are counted, and any rust spot larger than /8 inch hibitors are provided by the higher molecular weight polyin diameter is counted as 3 specks. The results of these butenes within this range. The products of the present tests are showninthe table.

TABLE Results, rust specks in oil phase Product of Example Lbs.[bbl. Fuel Other additives LbsJbbl. (average) 0 A Antioxidant 5 152 0 B 2.5 71 2.5 B 2.5 0 2.7 A 5 131 2.5 B 2.5 0 1.8 A 5 66 o 0 0 74 1.5 c 0 2 1.5 C o 22 1.5 c 0 73 1.5 c 7 a 1.5 o 7 s 1.5 o 7 18 1.5 o 7 46 1 Antioxidant, dispersant and metal deactivator.

It may be seen from the above table that the products of this invention are very effective corrosion inhibitors, providing almost complete rust protection. The lower molecular weight products, and the anhydrides do not provide the protection afforded by the compounds of the 5 instant invention.

What is claimed is:

1. A composition comprising: (a) a major amount of a distillate fuel; and (b) a minor amount of a rust inhibitor composition consisting essentially of a polybutene substituted succinic acid, said polybutene substituent having an average molecular weight in the range of 450 to 1100, said minor amount being sufiicient to impart rust inhibition to said composition.

2. The composition of claim 1 wherein said polybutene substituent has an average molecular Weight in the range of 700 to 900.

4 References Cited UNITED STATES PATENTS 2,334,158 11/1943 Von Fuchs et al. 44-70 XR 3,282,836 11/ 1966 Miller et al 4470 XR FOREIGN PATENTS 1,020,293 2/ 1966 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

W. I. SHINE, Assistant Examiner.

US. Cl. X.R. 

